1. Field of the Invention
The present invention relates to jet blast deflection fences for upwardly deflecting the horizontal blasts of various types of jet and turbo prop aircraft, and more particulary the present invention pertains to new and improved support structure that is of ultimate simplicity, aesthetically pleasing and saves valuable operational space. Longitudinal ventilating slots are included to reduce turbulence in order to improve deflection performance.
2. Description of the Prior Art
With the advent of the jet aircraft the areas in and around airports have been subjected to hazardous rearward jet blasts which are composed of hot gases that have been accelerated to high velocities. The hazard of the jet blast gave rise to the blast deflector fence which normally redirects the horizontal jet blast to a vertical direction in order to protect persons and property on the ground.
During the past thirty (30) years blast deflector fences have developed into expensive complex structures requiring many supporting members shaped into complex rib frames to which a corrugated steel deflecting surface is bolted. Heights of 6 feet to 8 feet were sufficient to deflect the blasts of commercial and military aircraft of 25 to 30 years ago, as a simple structure as illustrated in the U.S. Pat. No. 3,126,176 issued to B.S. Lynn, Mar. 24, 1964. However, with passing time, aircraft have been developed with more powerful engines with thrust centerlines of up to 32 feet or more above grade level. The average and most used height of deflector now at modern airports is 14 feet, rather than the 7 foot to 8 foot heights of 25 to 30 years ago. The 14 foot height requires numerous braces to form a rib truss, in addition to horizontal stringers across the back of the rib frames, and diagonal braces to prevent side to side movement or swaying, and to reduce vibration of the rib frames caused by the pulsating blasts, not always normal to the longitudinal axis of the deflector. Such supporting structure, for example, is illustrated in U.S. Pat. No. 4,471,924 issued to B.S. Lynn, Sep. 18, 1984.
In addition, airport operational aprons were not as expensive and crowded 25 years ago, so that fore and aft distances from front anchor bolts to rear anchor bolts were relatively large. In some cases, the base distance was about equal to the fence height to keep the overturning movement low in order to reduce uplift on the front anchor bolts, so that lighter and less expensive foundations could be used. Recently, however, shortcomings in modern deflectors became apparent: (1) Complaints were made by modern airports that the numerous braces required gave the structure an unfinished and unpleasing appearance and (2). The side base of the popular 14 foot high deflector (distance between front and rear anchor bolts) used up too much valuable space, as the larger aircraft and increased numbers of aircraft overcrowded the very costly parking ramps and operating areas. The improvements embodied in the present invention alleviate these problems and provide an improved deflector with clean, simple aesthetic lines, combined with a narrow base which actually creates more usable real estate on crowded operational aprons and other areas where jet blast deflector fences are required. In addition, the novel vertical strut hinged at the top permits a simple method of reducing or increasing the base width by simply relocating the anchor bolts, if desired.